Draft control and dust separator



March 7, 1933. 1. T. MARTIN DRAFT CONTROL AND DUST SEPARATOR Filed March 9, 1931 FIG- 1,.

INVENTOR. //?A 7' MAR TIN ATTORNEYS.

Patented Mar. 7, 1933 IRA. '1. MARTIN, OF SAN FRANCISCO, CALIFORNIA DRAFT con'raor. AND DUST SEPARATOR Application fil ed March 9, 1931. Serial No. 521,057.

This invention relates to apparatus for the control of stack draft somewhat similar to that shown in my oopending patent application filed under Serial No. 386,524 on I August 17, 1929, and has for its objects certain improvements over the prior apparatus wherebythe water tank may be dispensed with, and also wherebythe apparatus will efiectually separate dust or solid particles from the gases of combustion carried through the stack, especially suchstacks as used for cement kilns which" ordinarily discharge large quantities of fine dust. Other objects of the invention will appear in the following description and accompanying drawing.

In the drawing Fig. 1 isan elevation of a portion of a smoke stack showing my improved apparatus.

Fig. 2 is a cross sectional plan view of the receptacle under the stack'bend as seen from the line 2-2 of Fig. 1. i

Fig. 3 shows a closing plug for the lower end of the receptacle.

Before describing my inventionit might be stated that in the copending case the main smoke stack is provided with a side outlet fitted with a'downwardly curving return bend. which dips into a water tank, and the draft is controlled by a damper in the stack as well as by raising and lowering thewater level in the tank toshut off more or less the downwardly directed open end of the stack bend. In experimenting with many of these installations on industrial plants I have discovered that if the tank be suitably proportioned and the distance of projection of the stack bend intothe tank be made adjustable, that perfect draft control may be obtained without any water in the tank at all. Furthermore, if the tank is provided with a downwardly extending outlet leading to a dust collecting chamber that a very large percentage of flue dust, fly ash, etc., may be separated from. the gases, and the present disclosure is directed to the results of these discoveries. I

In the drawing 1 is a common vertical smoke stack ofany desired height and con- ,5 struction, 2 is a solid damper in the upper portion of the stack and adjustable to any dust to any desired form of dust collecting position by handle 2 or any other damper operating device.- At 3 is a side outlet from the stack or return bend with its downwardly curved open end 4 projecting into a funnelshaped receptacle 5 supported on a suitable rigid frame-work 6.

At an intermediate point in the return bend is a solid damper 7 suitably controlled or adjusted by a handle 7 or any other dam- 0 per operatingdevice, in fact both dampers may conveniently be operated by remote control devices as shown on the damper in the oopending case, as the particular means for operating these dampers has no inventive bearing on the invention herein claimed.

Receptacle 5 is provided with a cylindrical upper end 5' surrounding the lower end. of the return bend 4, and a downwardly extending central pipe 9 to carry the deposited chamber.

The receptacle is mounted on a plurality of vertical screws 10 working in nuts 11 sup ported on frame 6, and preferably all operated simultaneously by means of a chain 12 passing over sprockets 13 secured to each screw, and means being provided for moving the chain back and forth to effect the desired elevation of the receptacle, such means being here shownas a downwardly extending shaft or continuation 14 of one of the screws 10 which maybe turned from a remote point.

Besides providing for thus elevating or lowering the receptacle in relation to the open end of the return bend, I provide a separate telescopic lower section 4 on thereturn bend which may be raised and lowered in the same manner as described for the receptacle.

The telescopic section 4' of the return bend fits loosely inside or outside of the lower section 4 and is suspended on outwardly bent arms 15 from a circular frame or'spider 16 which at its outer margins is supported on'a plurality of vertical screws 17 passing through bearing nuts 18 secured to the. sides 5' of the receptacle and all actuated simultaneously by a chain 19 passing over sprockets 20 secured to the screws. One of the, screws may be extended as at 17 for turning from below to raise or lower the telescopic end 4 of the bend.

The extreme lower open end of the telescopic portion 4 terminates at an angle as indicated, but this is of particular use in such installations where water is used in the receptacle 5, and which may be done after lowering a sealing plug into the lower conical end of the receptacle. Such a plug is shown in cross section at 21 in Fig. 3 and is made of heavy metal with a soft gasket 22.

With the above apparatus, proportioned substantially as shown, it has been found possible to effect almost as perfect a draft control as though water was used in the receptacle to seal the lower end of the bend. This is due to the'fact that when damper 2 is closed and 7 open the stack gases from the furnace pass downwardly through the bend, while curving upwardly in the receptacle to escape freely around its periphery, but if the telescopic end of the bend be lowered into the receptacle, or the receptacle be raised, eddies are set up in the expanding gases in such a manner that the gases develop a considerable back pressure and escape with difficulty.

When the telescopic end is close to the top of the receptacle a test with a thermometer will show the hottest zone to lie close to the outer edge of the cylindrical portion 5 of the receptacle, and with a cool area nearer the pipe, but when the projection into the receptacle is increased the hot space extends across the entire upper open area and with fitful escape of the hot gases at various points, thus showing that the eddies formed obstruct to a great extent the outward flow, of hot gases.

There is also produced a steady precipitation of the dust content of the gases which falls in a stream down pipe 9 for collection in any desired form of dust collecting chamber. The dust separating feature of the apparatus is remarkable in its ability to separate a high percentage of fine ash, and this is thought due to the solid particles carried by the gases being thrown outwardly by centrifugal action in passing through the bend so as to greatly reduce their speed and concentrate them against the outer wall. of the bend from which they fall to pipe 9.

The solid particles carried by the gases when escaping from the nozzle or lower end of the bend are directed downwardly into a gas pocket formed in the receptacle in which there is practically no vertical motion, on the contrary, the pressure due to the downward stream of gas, causes a portion of the gases to be expelled through the waste pipe 9 and if so desired an induced gas travel can be maintained in a downward direction by attaching an exhaust fan to waste pipe 9. The only particles then escaping from the upper end of the open damper tank are such as are capable of being borne on gas having little or no kinetic energy.

By suitably adjusting damper 7 the gases may be further directed toward the outer wall of the bend, and also retarded to any desired extent, and to gain the maximum in dust separation damper 2 is kept closed after the initial draft is once established.

To further assist in the collection of these lighter particles, where the stack temperature is sufiiciently high, a spray nozzle 23 or small water jet can be placed in the return bend and the water entering through this means being converted into steam, increases the humidity of the escaping gases and the affinity of the lighter particles for moisture causes them to absorb a portion of the moisture so supplied thereby increasing their specific gravity as well as giving them a tendency to adhere one to another, thereby materially assisting in their recovery.

Damper 24 is placed in the discharge pipe for the purpose of controlling the escapmg gases from the bottom of the tank into the bin or settling chamber.

With the construction above noted, it will be seen that contraction and expansion of" the main stack, which if very tall and of steel, may be considerable, will not affect the adjusted relation of the lower end of the return bend, as this is an independent telescopic section 4 carried on the fixed frame 6 which also supports the receptacle 5. This is an important feature of my invention.

Attention is called to the fact that while I show vertical screws for adjusting the telescopic end of the return bend, and the re ceptacle up and down, any number of simple arrangements may be employed for this pur pose.

It is also obvious that instead of. placing the vertically movable telescopic section on the lower end of the return bend, it may be a telescopic section on the upper end of the receptacle, but I prefer the arrangement shown as its adjustment is not affected by expansion and contraction of the main stack.

I claim 1. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return. bend extends, and means for varying the eflfective extension of the return bend into said receptacle.

2. Draft control apparatus. comprising a main stack provided with a side-outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends, and means operable from a remote point for varying the effective extension of the return bend into said receptacle.

3. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends, means for varying the effective extension of the return bend into said receptacle, and a pipe extending downwardly from said receptacle adapted to receive the dust precipitated from flue gases emerging from said stack.

4. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends, means for varying the effective extension of the return bend into said receptacle while preserving the freedom of bodily movement of the return bend due to expansion and contraction.

5. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends, means for varying the effective extension of the return bend into said receptacle, a pipe extending downwardly from said receptacle adapted to receive the dust precipitated from flue gases emerging from said stack, and a damper in said pipe.

6. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends, and means for bodily raising and lowering said receptacle.

7. Apparatus as specified in claim 1, a damper in said return bend, and a damper in said stack above said return bend.

8. Apparatus as specified in claim 1, a damper in said return bend, and a damper in said stack above said return bend, said damper in the return bend arranged for defiecting the gases against the outer wall of the return bend.

9. Apparatus as specified in claim 1, a damper in said return bend, a damper in said stack above said return bend, a dust-receiving pipe extending downwardly from said receptacle, and a damper in said pipe.

10. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends, and vertical screws on which said receptacle is supported whereby the receptacle may be raised and lowered.

11. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends, vertical screws on which said receptacle is supported whereby the receptacle may be raised and lowered, and means for simultaneously operating said vertical screws.

12. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, areceptacle into which the lower end of said return bend extends, means for varying the effective extension of the return bend into said receptacle comprising a separate telescopic section at the lower end of said return bend, and means for raising and lowering said telescopic section.

18. Draft control. apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends,

means for varying the effective extension of the return bend into said receptacle comprising a separate telescopic section at the lower end of said return bend, a spider supporting said telescopic section, and means supporting said spider for vertical movement.

14. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends, means for varying the eifective extension of the return bend into said receptacle comprising a separate telescopic section at the lower end of said return bend, a spider supporting said telescopic section, and a plurality of vertical screws supporting said spider arranged for raising and lowering the spider together with said telescopic section.

15. Draft control apparatus comprising a main stack provided with a side outlet fitted with a downwardly extending return bend open at its lower end, a receptacle into which the lower end of said return bend extends, means for varying the effective extension of the return bend into said receptacle comprising a separate telescopic section at the lower end of said return bend, and means operable from a remote point for raising and lowering said telescopic section.

16. Apparatus of the character described comprising a stack provided with a downwardly extending return bend, an opentopped empty receptacle into which the lower end of the bend extends, of such a size to permit flow of hot gases from the lower end of the return bend outwardly and upwardly around the bend and out of the receptacle, a dust discharge pipe extending downwardly from said receptacle, the proportions and depth of said receptacle relative to said return bend being such as to cause a relatively quiescent gas zone through which dust will be precipitated into said pipe from gases passing out of said return bend.

IRA T. MARTIN. 

